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New Haven fire officials said the initial call was for a hydrogen cyanide explosion. Once they were on the scene they determined it was actually a natural gas leak. Officials said there was a container of sodium bisulfite had ruptured and material was on the ground. The chemical is not harmful or an explosive but it can be an irritant. They believe the chemical's container was damaged as a result of the explosion. Power in the area was shut down briefly.

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Everyone in the building was accounted for, and two people in vicinity of explosion were treated on scene for shock and released.

The Amtrak line near the building was shut down briefly to clear debris, but has since reopened.

Hazmat crews are also responding according to New Haven Fire's Twitter.

The business at that location is listed as H. Krevit & Company. According to their website, they manufacture cleaning and sanitizing chemicals.